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.\" Copyright (c) 2012 Bjoern A. Zeeb <bz@FreeBSD.org>
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.Dd October 16, 2019
.Dt WBWD 4
.Os
.Sh NAME
.Nm wbwd
.Nd device driver for Winbond/Nuvoton Super I/O chips watchdog timer
.Sh SYNOPSIS
To compile this driver into the kernel, place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device superio"
.Cd "device wbwd"
.Ed
.Pp
Alternatively, to load the driver as a module at boot time, place the following
line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
wbwd_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides
.Xr watchdog 4
support for the watchdog interrupt timer present on at least the following
Super I/O chips:
.Bl -bullet -compact
.It
Winbond 83627HF/F/HG/G
.It
Winbond 83627S
.It
Winbond 83697HF
.It
Winbond 83697UG
.It
Winbond 83637HF
.It
Winbond 83627THF
.It
Winbond 83687THF
.It
Winbond 83627EHF
.It
Winbond 83627DHG
.It
Winbond 83627UHG
.It
Winbond 83667HG
.It
Winbond 83627DHG-P
.It
Winbond 83667HG-B
.It
Nuvoton NCT6775
.It
Nuvoton NCT6776
.It
Nuvoton NCT6102
.It
Nuvoton NCT6779
.It
Nuvoton NCT6791
.It
Nuvoton NCT6792
.El
.Sh SYSCTL VARIABLES
The
.Nm
driver provides the following options as
.Xr sysctl 8
variables.
.Bl -tag -width "xxxxxx"
.It Va dev.wbwd.0.timeout_override
This variable allows to program the timer to a value independent on the one
provided by the
.Xr watchdog 4
framework while still relying on the regular updates from e.g.
.Xr watchdogd 8 .
This is particularly useful if your system provides multiple watchdogs and
you want them to fire in a special sequence to trigger an NMI after a shorter
period than the reset timeout for example.
The value set must not be lower than the sleep time of
.Xr watchdogd 8 .
A value of 0 disables this feature and the timeout value provided by
.Xr watchdog 4
will be used.
.It Va dev.wbwd.0.debug_verbose
If set this sysctl will tell the driver to log its current state before and
after the timer reset on each invocation from
.Xr watchdog 9
to the kernel message buffer for debugging.
.It Va dev.wbwd.0.debug
This read-only value gives the state of some registers on last update.
.El
.Pp
The
.Nm
driver also provides further sysctl options that are hidden by default.
See the source code for more information.
.Sh SEE ALSO
.Xr superio 4 ,
.Xr watchdog 4 ,
.Xr device.hints 5 ,
.Xr watchdog 8 ,
.Xr watchdogd 8 ,
.Xr watchdog 9
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 10.0 .
.Sh AUTHORS
.An -nosplit
This manual page was written by
.An Bjoern A. Zeeb Aq Mt bz@FreeBSD.org .
